Block 6 Anatomy Inguanal Region Umich W Expl

The ilioinguinal nerve enters the inguinal canal from the side (instead of passing through the deep inguinal ring). It leaves the inguinal canal by passing through the superficial inguinal ring to exit the canal, so it might be injured during inguinal hernia repair. The femoral branch of the genitofemoral nerve travels lateral to the superficial inguinal ring. The iliohypogastric nerve and the subcostal nerve travel superior to the inguinal canal and superficial inguinal ring. Finally, the obturator nerve is a branch of the lumbar plexus which innervates muscles in the thigh. To reach the thigh, this nerve travels deep to the inguinal canal, and it is not involved with this region. See Netter Plate 249 for an illustration of these nerves.

An indirect inguinal hernia leaves the abdominal cavity lateral to the inferior epigastric vessels and enters the inguinal canal through the deep inguinal ring. Commonly, these hernias traverse the entire inguinal canal, leave the canal through the superficial inguinal ring, and enter the scrotum. The indirect inguinal hernias are the most common type of hernia, and are often caused by heavy lifting. Direct inguinal hernias leave the abdominal cavity medial to the inferior epigastric vessels, through the weak fascia. These usually do not traverse the entire inguinal canal, and they rarely enter the scrotum. Direct inguinal hernias may be caused by a weakness of abdominal musculature.

You can't tell if an inguinal hernia is direct or indirect just by palpating it! Although indirect hernias are the ones that usually come out of the superficial inguinal ring and enter the scrotum, direct inguinal hernias might do this too! As for the other answers... a femoral hernia goes through the femoral ring into the femoral canal--it has nothing to do with the superficial inguinal ring. A superficial inguinal lymph node lies in the superficial fascia, parallel to the inguinal ligament. It would feel more superficial and should not be mistaken for a hernia protruding through the inguinal ring.

The inguinal triangle is the site for direct inguinal hernias. It is defined medially by the lateral border of rectus abdominus, inferiorly by the inguinal ligament, and superiorly by the inferior epigastric artery.

A direct inguinal hernia is caused by a weakness in the abdominal muscles which prevents a patient from contracting these muscles strongly. If this patient can't contract his muscles, he can't pull the falx inguinalis down to cover the thin area of weak fascia on the posterior wall of the inguinal canal. The ilioinguinal nerve is important for innervating the muscles of the lower abdominal wall. So, if this nerve was damaged during the appendectomy, the man might not be able to contract his abdominal muscles and pull the falx inguinalis over the weak fascia. This could have led him to develop the direct inguinal hernia.
The genitofemoral nerve innervates the cremaster muscle. An injury to this muscle would lead to an inability to elevate the testes, but it would not compromise the strength of the abdominal wall. The subcostal nerve and the ventral primary ramus of T10 innervate muscles, skin & fascia of the abdominal wall above the inguinal region. The anterior cutaneous branch of T10 reaches the umbilicus specifically.

In females, the round ligament of the uterus is the main structure traversing the inguinal canal. In males, the most important structure in the inguinal canal is the spermatic cord. The iliohypogastric nerve innervates the abdominal wall. It runs between the transversus abdominis and internal oblique muscles, then pierces the internal oblique at the anterior superior iliac spine to run between the internal and external obliques. The inferior epigastric artery lies between the peritoneum and the transversus abdominis, creating the lateral umbilical fold. The ovarian artery and vein are branches from the descending aorta and inferior vena cava which supply the ovary in the pelvis. The pectineal ligament is a thick layer of fascia over the pectineal line of the pubis. Although the pectineal ligament helps define the boundaries of the inguinal canal, you can't really say that the pectineal ligament traverses the canal. That's why the round ligament is the best answer.

The superficial inguinal ring is a slit-like opening between the diagonal fibers of the external abdominal oblique. It is bounded by the medial and lateral crus, and it forms the exit of the inguinal canal. The falx inguinalis is composed of arching fibers of the internal abdominal oblique and the transversus abdominis. It forms the roof of the inguial canal, and the posterior wall medially where it inserts as the conjoint tendon (onto the pubic crest and medial part of the pectineal ligament. Scarpa's fascia is the membranous layer of subcutaneous fascia. Finally, transversalis fascia is found laterally on the posterior wall of the inguinal canal, forming the area of weak fascia in that wall.

Indirect inguinal hernias cross through the deep inguinal ring, passing deep to the internal spermatic fascia. This means that they can enter the scrotum fairly easily, and indirect inguinal hernias are often found in the scrotum. Direct inguinal hernias are not covered by the internal spermatic fascia; they enter the inguinal canal next to the spermatic cord, and rarely enter the scrotum. (However, direct inguinal hernias can enter the scrotum on rare occasion, so don't assume that you are dealing with an indirect inguinal hernia just because it has entered the scrotum.) A femoral hernia is protrusion of abdominal viscera through the femoral ring into the femoral canal. It appears as a mass in the femoral triangle, inferolateral to the pubic tubercle. An obturator hernia is a protrusion of a loop of bowel through the obturator canal.

The ilioinguinal nerve runs in the inguinal canal, so this nerve could easily be compressed by an inguinal hernia. The ilioinguinal nerve also gives off the anterior scrotal nerve, which is the nerve responsible for sensory innervation to the anterior scrotum. The location of this hernia and the scrotal pain both fit with an injury to the ilioinguinal nerve.
The femoral branch of the genitofemoral provides sensory innervation to the upper medial thigh. The femoral nerve innervates the anterior compartment of the thigh, and has some cutaneous sensory branches to the thigh. The iliohypogastric nerve innervates the skin of the lower abdominal wall, upper hip, and upper thigh. Finally, the subcostal nerve is the ventral primary ramus of T12, which innervates the skin of the anterolateral abdominal wall.

The boundaries listed in this question are the boundaries of the inguinal triangle, which is the site for direct inguinal hernias. Remember--direct inguinal hernias protrude through the weak fascia of the abdominal wall, medial to the inferior epigastric vessels. Indirect inguinal hernias (which can also be called congenital inguinal hernias) occur lateral to the inferior epigastric vessels--they protrude through the deep inguinal ring. Femoral hernias protrude through the femoral ring, into the femoral canal. They can be felt in the femoral triangle, inferior to the pubic tubercle. Finally, an umbilical hernia is an abnormal protrusion of abdominal contents into a defect in the umbilical area. These are common in the newborn, but they usually resolve by age two.

A direct inguinal hernia passes through the weak fascia in the medial inguinal fossa. This is the area between the medial and lateral umbilical folds (made of the obliterated umbilical artery and inferior epigastric vessels, respectively). A direct inguinal hernia does not pass through the deep inguinal ring or the lateral inguinal fossa--that's what an indirect hernia does. Although it's much more common for an indirect hernia to pass through the superficial inguinal ring, direct hernias could go through this ring too. However, the question is asking you to identify which region the hernia enters on the abdominal side, so superficial inguinal ring is not the correct answer. The supravesicular fossa is between the median and medial umbilical folds--it is formed where the peritoneum reflects from the anterior abdominal wall onto the bladder. Potentially, a very rare external supravesicular hernia could form here.

The sigmoid colon is the most likely intestinal segment to be involved in a left-sided indirect inguinal hernia. Although the descending colon is also on the left side of the abdomen, it is a bit superior to be herniating through the deep inguinal ring. The ascending colon and cecum are on the right side of the abdomen, so they would not be involved with a left sided hernia. Finally, the rectum is a structure in the pelvis; it is too inferior to enter the deep inguinal ring and cause an indirect inguinal hernia.

The round ligament of the uterus passes through the deep inguinal ring and runs through the inguinal canal. It is a derivative of the gubernaculum, a structure which pulled the gonads into place during embryonic development. In males, the scrotal ligament is what remains from the gubernaculum. Also keep in mind that, in males, the spermatic cord passes through the deep inguinal ring. Of the other answer choices, the ilioinguinal nerve is the only other one that courses through the inguinal canal. Remember--it leaves through the superficial ring and gives off the anterior labial or scrotal branch as a cutaneous continuation. However, the ilioinguinal nerve does not pass through the deep ring - it enters the inguinal canal on the side.
The iliohypogastric nerves run between the internal oblique and transversus abdominis in the abdominal wall, piercing the internal oblique at the anterior superior iliac spine to travel deep to just the external oblique. The inferior epigastric artery runs between the transversus abdominis and the peritoneum, forming the lateral umbilical fold. The medial umbilical ligament is the obliterated umbilical artery--it lies within the medial umbilical fold of peritoneum.

Remember, the medial umbilical fold is made by the medial umbilical ligament (the obliterated portion of the umbilical artery), while the lateral umbilical fold is a fold of peritoneum over the inferior epigastric vessels. The median umibilical fold is a midline structure made by the median umbilical ligament (obliterated urachus). The medial inguinal fossa is the space on the inner abdominal wall between the medial umbilical fold and the lateral umbilical fold. This is the place in the abdominal wall where there is an area of weak fascia called the inguinal triangle--direct inguinal hernias can break through this space. The lateral inguinal fossa is a space lateral to the lateral umbilical fold--indirect inguinal hernias push through the deep inguinal ring in this space.

The deep inguinal ring is found near the midpoint of the inguinal ligament, below the anterior superior iliac spine. This ring is lateral to the inferior epigastric artery. The superficial inguinal ring is found above the pubic tubercle. Remember--the supravesical fossa is the space between the median and medial umbilical folds.

You can't tell if a hernia is direct or indirect just by palpating it! Although it is more common for indirect hernias to pass through the superficial inguinal ring while direct hernias usually stay in the inguinal canal, it is possible that a direct hernia could protrude through the superficial ring and even enter the scrotum.

To understand this question, you need to understand the descent of the testes. The testes begin as retroperitoneal structures in the posterior abdominal wall. They are attached to the anterolateral abdominal wall by the gubernaculum. The gubernaculum "pulls" the testes through the deep inguinal ring, inguinal canal, superficial inguinal ring, and over the pelvic brim. The gubernaculum is preceded by the processus vaginalis, which is derived from the peritoneum anterior to the testes. The processus vaginalis "pushes" the muscle and fascia layers, which will eventually make up the canal and spermatic cord, into the scrotum. After the testes are in position in the scrotum, the gubernaculum persists as the scrotal ligament, while part of the processus vaginalis remains as a bursa-like sac called the tunica vaginalis testis. So, the testes could get caught in the deep inguinal ring, inguinal canal, at the superficial inguinal ring, or at the pelvic brim. The testes are never in the perineum, and they wouldn't get stuck there.

The internal spermatic fascia is derived from the transversalis fascia. As the testes descend through the deep inguinal ring, the transversalis fascia is pulled along, forming the innermost covering of the spermatic cord. So, in an adult, the spermatic cord is lying in the inguinal canal, covered by the internal spermatic fascia. Now, think about what happens in the direct inguinal hernia--a piece of bowel begins to protrude through the weak fascia on the posterior wall of the inguinal canal. But at that location, the spermatic cord is already lying in the inguinal canal, covered by the internal spermatic fascia. This means that the direct inguinal hernia will lie next to the spermatic cord, but it cannot enter the spermatic cord. In contrast, an indirect inguinal hernia passes through the deep inguinal ring, and it will be covered by the internal spermatic fascia of the spermatic cord.
Both types of hernias are covered by the external spermatic fascia, the peritoneum, and extraperitoneal connective tissue. The direct inguinal hernia passes through the weak fascia of transversus abdominus, so it would be covered by that layer which is absent from an indirect inguinal hernia.

The inferior epigastric vessels lay on the inner surface of the transversus abdominis and are covered by parietal peritoneum. Remember, the peritoneum lies over the inferior epigastric vessels to make the lateral umbilical fold. Camper's fascia and Scarpa's fascia are two layers of the superficial fascia - Camper's is the fatty layer and Scarpa's is the membranous layer.